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Bitesize GCSE Science - Physics
Space
Astronomer at the Royal Observatory Greenwich, Tom Kerss on
satellites
A satellite is any object that orbits around what we would call a superior body,
that just means another object which is bigger or heavier than the satellite
itself.
So we place satellites in orbit around the Earth, what we do is we build space
craft, we launch them up on rockets and they are designed to orbit the Earth,
which means that they don’t just fly out into space they stay with the Earth as
the Earth makes its orbit around the Sun and then they can communicate to
us here on the surface of the Earth and they can also be used to transmit
communications over long range.
Satellites really have transformed the world, we’re talking about satellites that
allow us to use phones for example over long distance or to transmit internet
to remote places but we also use satellites to position ourselves on the
Earth’s surface, things like GPS.
We also use them to monitor the Earth’s climate and the surface of the Earth
so that we can look at natural disasters when they occur and we can generate
photographs of the Earth and see how it is changing.
Quite often when we talk about satellites what we actually mean to say is
artificial satellites because we are really talking about space craft. The Moon
for example is a natural satellite because we didn’t make it but it does orbit
the Earth, which is bigger and heavier than itself, and in fact we can go further
and say that all the planets are natural satellites of the Sun and their moons
are also natural satellites of those planets.
So artificial satellites are sent in to space by us, natural satellites are already
there but they both obey the same principal, they both orbit larger bodies in
space.
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